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Calculator start selection

Read all about available
deployments.
In any way of utilizing calculator, Internet connection is required, for authentication at least.

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Available in download version

save/open multiple results

export to word and excel

print results

custom fluid properties

K factor for fittings, resistance coefficient

pipe surface roughness selection

select between gauge and absolute pressure

compressible isothermal flow

dry air isothermal flow

gas offtake flow

natural gas flow

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When is this calculator suitable?

To select a size of a gas control valve, you should calculate the required flow coefficient Cg
or Kg for the given flow rate and pressure drop.

For a specific gas control valve, the flow coefficient Cg or Kg is determined experimentally
by control valve manufacturers, and you can found it in manufacturers technical specifications.
They express flow coefficient Cg or Kg as the flow rate of water in g.p.m. [m3/h] for a pressure
drop of 1 psi [1 bar] across a flow passage [flow coefficient: Cg-imperial, Kg-metric].

You can calculate the gas control valve capacity for given upstream and downstream pressure
and known flow coefficient Cg or Kg.

With maximum flow rate calculated, you can compare capacities of control valves from different
manufacturers with the same nominal size.

Standard EN334 is covering gas control valves and pressure regulators for pressures up to
100 bar. The calculator is in line with the same standard.

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When is this calculator not relevant?

You should use a flow coefficient calculator for an incompressible flow of liquids.

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How is the calculation executed?

The calculator is calculating flow coefficient Cg or Kg using the relationship between
pressure drop and flow rate in the control valve which is for complete turbulent flow
following power law where flow coefficient is the proportional constant:

where is:

q - flow rate

Cg - flow coefficient

Δp - pressure drop

# Need a helping hand?

If you need a quick calculation, but you are not still familiar how to use the calculator, you
can order calculation service from the calculator developer.